1. Field of Invention
The present invention relates to IEEE 802.21 Media Independent Handoff (MIH), and its instantiation in a IEEE 802.11 Wireless Local Area Network (WLAN), a IEEE 802.16 Broadband Wireless Access Network (BWA) and over L3 Internet Protocol (IP); and more particularly, relates to a mechanism or technique for one media independent handoff function (MIHF) to discover events or a type of information available in another MIHF in relation to the same.
2. Problem in the Art
FIG. 1 shows, by way of example, typical parts of an IEEE 802.11 WLAN system, which is known in the art and provides for communications between communications equipment such as mobile and secondary devices including personal digital assistants (PDAs), laptops and printers, etc. The WLAN system may be connected to a wire LAN system that allows wireless devices to access information and files on a file server or other suitable device or connecting to the Internet. The devices can communicate directly with each other in the absence of a base station in a so-called “ad-hoc” network, or they can communicate through a base station, called an access point (AP) in IEEE 802.11 terminology, with distributed services through the AP using local distributed services set (DSS) or wide area extended services (ESS), as shown. In a WLAN system, end user access devices are known as stations (STAs), which are transceivers (transmitters/receivers) that convert radio signals into digital signals that can be routed to and from communications device and connect the communications equipment to access points (APs) that receive and distribute data packets to other devices and/or networks. The STAs may take various forms ranging from wireless network interface card (NIC) adapters coupled to devices to integrated radio modules that are part of the devices, as well as an external adapter (USB), a PCMCIA card or a USB Dongle (self contained), which are all known in the art.
FIGS. 2a and 2b show diagrams of the Universal Mobile Telecommunications System (UMTS) packet network architecture, which is also known in the art. In FIG. 2a, the UMTS packet network architecture includes the major architectural elements of user equipment (UE), UMTS Terrestrial Radio Access Network (UTRAN), and core network (CN). The UE is interfaced to the UTRAN over a radio (Uu) interface, while the UTRAN interfaces to the core network (CN) over a (wired) Iu interface. FIG. 2b shows some further details of the architecture, particularly the UTRAN, which includes multiple Radio Network Subsystems (RNSs), each of which contains at least one Radio Network Controller (RNC).
The interworking of the WLAN (IEEE 802.11) shown in FIG. 1 with other technologies (e.g. 3GPP, 3GPP2 or 802.16 (BWA)) such as that shown in FIGS. 2a and 2b is being defined at present, for example, in protocol specifications for 3GPP and 3GPP2. In IEEE protocol specification, such activities are carried out in IEEE 802.11 TGu and in IEEE 802.21 (the latter specification focusing specifically on the handoff of a device).
In the IEEE 802.21 Protocol Specification, a set of events is defined, to define which triggers the MIHF can deliver to the logical functions that subscribe to such events. Specifically, in IEEE 802.21 one logical functionality (e.g. L3 mobility protocol, applications, connection manager, handoff controller) can subscribe with the MIHF to receive event notifications (triggers) related to certain events (e.g. a link layer is up, signal quality is below a certain threshold, etc.) The subscribing logical entity can be local, thus capable of performing local event subscription (within a specific entity, e.g. the MIH Function—MIHF—in the terminal), or remote, thus capable of performing remote event subscription (between e.g. the MIHF in the terminal and the MIHF in the network) will be specified in document [1] below).
For a remote MIHF to be able to subscribe to events in another entity (e.g. specifically for the MIHF in the network to be able to subscribe to events in the terminal through the MIHF in the terminal), the MIHF in the network must know which events are available in the terminal. In fact, it is expected that not all events supported by 802.21 will be meaningful and available for all terminal, depending on the access technology, e.g. 802.11 (WLAN), 802.16 (WBA), 3GPP, 3GPP2, etc.
Similarly, one entity can request information from a remote entity through the 802.21 MIH Information Service. However, how does one MIHF know what information is available and what is not from another MIHF?
The reader is referred to the following documents, which are hereby incorporated by reference in their entirety herein:
[1] IEEE 802.21 document 21-04-0087-12-0000, “IEEE P802.21 Media Independent Handover Service Draft Technical Requirements”;
[2] 3GPP TS 32.602: “Telecommunication management; Configuration Management (CM); Basic CM Integration Reference Point (IRP): Information Service (SS)”; and
[3] 3GPP TS 32.612: “Telecommunication management; Configuration Management (CM); Bulk CM Integration Reference Point (IRP): Information Service (IS)”.